Silicone slurry is a fluid or semi-fluid material based on silicone rubber or organosilicon compounds, which is processed and formulated. It has unique physical and chemical properties and plays an important role in many industrial fields. The following is an introduction from the dimensions of material properties, application fields, preparation and processing:
Material properties
Chemical structure and composition
The core component of silicone slurry is an organosilicon polymer with a silicon-oxygen bond (Si-O) main chain, and the side chain may be connected to organic groups such as methyl and vinyl.
Depending on the purpose, conductive particles (such as silver powder, carbon nanotubes), fillers (silicon dioxide), pigments or functional additives (such as flame retardants) may be added to the slurry.
Physical properties
Flowability: Flexible control from high viscosity paste to low viscosity liquid can be achieved by adjusting the solid content and viscosity.
Thermal stability: It has a wide temperature range of -50℃ to 250℃, and the short-term temperature resistance can reach 300℃.
Electrical properties: The volume resistivity of conductive paste can be as low as 10⁻³Ω·cm, which meets the requirements of electromagnetic shielding; the volume resistivity of insulating paste is >10¹⁵Ω·cm.
Mechanical properties: After curing, it forms an elastomer with a Shore hardness of 20-80A, an elongation at break of 100%-800%, and a tear strength of 5-50kN/m.
Application areas
Electronics and electrical
Electromagnetic shielding: Conductive silicone paste is applied to the housing of electronic equipment by screen printing to achieve a shielding effectiveness of 30-80dB (10MHz-3GHz).
Flexible circuit: As a conductive line ink, it is used on flexible substrates of wearable devices and folding screens, with a line width accuracy of up to 50μm.
Packaging protection: High thermal conductivity silicone paste (thermal conductivity 0.8-3.0W/m·K) is used for potting of power devices to reduce thermal resistance by 40%.
New energy
Photovoltaic modules: Fill the gap between the cells with transparent silicone slurry, with a light transmittance of >95%, and increase the power output of the module by 2%-3%.
Power battery: As the airtight sealing material of the battery pack, it meets the IP67 protection level requirements, and the electrolyte corrosion resistance has passed the 500h test.
Medical health
Implanted devices: Medical-grade silicone slurry has passed ISO 10993 biocompatibility certification and is used to manufacture artificial heart valves, catheters, etc., with a tensile strength of >5MPa.
Wearable devices: Conductive silicone electrodes composited with fabrics, with skin contact impedance <1kΩ, meet the needs of ECG monitoring.
Advanced manufacturing
3D printing: Photocurable silicone slurry (viscosity 500-3000cPs) can achieve 25μm layer thickness printing for microfluidic chip manufacturing.
Precision mold: Silicone mold prepared by casting molding process, with a replication accuracy of ±0.02mm and a service life of >500 times.
Preparation and processing
Formula design
Base polymer: Vinyl silicone oil (viscosity 500-5000cPs) and hydrogen silicone oil (hydrogen content 0.5%-1.6%) are selected as the crosslinking system.
Catalyst: Platinum catalyst (concentration 5000-10000ppm) controls the vulcanization speed, and inhibitors (such as ethynyl cyclohexanol) are used to adjust the operation time.
Filler treatment: Fumed silica is surface modified by hexamethyldisilazane, and the addition amount of 10%-40% can significantly improve the mechanical properties of the slurry.
Processing technology
Screen printing: Use 300 mesh polyester screen, scraper hardness 60-70 Shore A, printing speed 10-30mm/s, and achieve 10-50μm film thickness control.
Curing conditions: The heat-cured slurry needs to be cured at 150℃×30min, and the addition-cured type can achieve second-level curing through UV-LED (365nm, 2J/cm²).
OPERATION SUGGESTIONS
1. Mesh: 100 mesh;
2. Print twice directly, leave a little thick paste in the pattern position of the net, lift the plate gently, and dry it in a table dryer. If tunnel drying is required, it must be dried on the surface. Note: The cloth cannot be collected if it is not completely dry, otherwise the printing position will be deformed. It can be dried naturally for 24 hours or dried in a tunnel dryer at 130-150 degrees for 2-3 minutes; the actual operation can be determined according to the printing requirements.
3. Washing test can be done only after the printed pattern is completely dry.
Post-processing: After curing, the product can be processed again, such as laser cutting with an accuracy of ±0.05mm, or plasma treatment to increase the surface energy to 72 dynes.